For example the mixture of 1 part of dark couverture chocolate (finely chopped) and 1 part of hot heavy cream... stir until the chocolate melts.Set aside for cooling until the mixture is firm enough for piping out.

If you have warm hands, you can melt the chocolate discs, put them in a piping bag, and pipe that way. The problem is when the chocolate starts to get hard. I have used a plastic tip on my bag, and thrown it in the microwave to warm it back up. I have also had a pot of hot water beside me, and put the bag in the water, in between times.